The present invention relates to an apparatus for processing digital data in a vertical blanking interval (hereinafter referred to as VBI) which is used as a character data inserting region of a video signal, in a video tape recorder (hereinafter referred to as VTR).
A conventional VTR which has the function of processing digital data in the VBI of an analog video signal is, for example, disclosed in Japanese Laid-open Patent No. H8-505729.
FIG. 14 is a block diagram showing the structure of the conventional digital data recording and reproducing apparatus. The apparatus comprises a tuner 202 for demodulating a broadcasting radio wave received through an antenna 201 into an analog video signal, a VBI decoder 203 for demodulating a digital signal existing in the VBI of the analog signal of a broadcasting television signal and a digital signal existing in the VBI of an analog video signal reproduced from a magnetic tape into character data, a VBI encoder 204 for producing a digital signal from character data for recording into a magnetic tape, a VTR control circuit 205 for controlling the drive of a VTR, a microprocessor control device 206 for general control of the VTR, a RAM (random access memory) 207 for storing character data, a motor and mechanism control circuit 208 for driving the hubs of a cassette 215, a video circuit 209 for recording and reproducing an analog video signal, a position counter 210 for detecting a tape position from the rotation of a pinch roller 214 which drives a magnetic tape 213, and a transformer coil 212 through which a signal is given and received to and from a video head mounted in a video head drum 211 which rotates the video head helically against the magnetic tape 213.
The operation of the above conventional apparatus is described hereinafter. In the apparatus, the title of a program to be recorded is extracted from the VBI of the analog video signal of a broadcasting television signal and stored in the RAM207. On the other hand, a cassette number in form of a digital signal is inserted into the VBI of the analog video signal to be recorded. And the cassette number is extracted at the occasion of reproducing the recorded video signal. By the above arrangement, the program title corresponding to the cassette number is selected and displayed on a television screen. More details are as follows.
(1) A user sets for recording reservation with a timer of the VTR. (2) During the recording, a cassette number in the form of a digital signal is inserted into the VBI of an analog video signal and recorded together with an video signal. (3) During the recording or in advance to the recording, a program title is extracted from the VBI of the analog video signal of a broadcasting radio wave and stored in the RAM 207 together with the cassette number and recording start position data on a magnetic tape. (4) At the stage of taking out the cassette from the VTR after finishing the recording, the user can recognize the cassette number on a television screen and can write by hand the cassette number on the label of the cassette. (5) The user inserts the cassette into the VTR to see the recorded program. (6) The VTR automatically works for reproducing on the magnetic tape for a few seconds and extracts the cassette number recorded in the VBI. (7) The program title corresponding to the cassette number is read out from the RAM 207 and displayed on a television screen together with the cassette number. (8) The recording start position in the magnetic tape on the program having the title selected by the user is read out from the RAM 207, and, the magnetic tape is first-forwarded or rewinded and set at the starting position of the selected program for reproduction. Also, by displaying cassette numbers and program titles stored in the RAM 207 on a television screen, a cassette in which a desired program is recorded can be found out.
FIG. 15(a) shows a conventional signal recorded in a VBI. The signal comprises a horizontal sync signal (HSYNC) 216, a color burst signal 217 for showing reference color phase, a clock run-in signal 218 for adjusting phase at the occasion of reading out a digital signal, a frame code signal 219 for identifying the starting position of the digital signal, and a two-byte (16-bit) digital signal 220 to be recorded.
FIG. 15(b) shows digital data recorded in the VBI. The digital data comprises a start code 221 for showing the starting position of a data row, a type code 222 for identifying the contents of the data row, data contents 223, an end code 224 for showing the end of the data contents 223, and check sum 225 for finding data error which occurs in recording and reproduction. As shown in FIG. 15(a), two bytes each of the data row shown in FIG. 15(b) are recorded in one horizontal scanning line of the VBI. In this case, the line number for the recording is predetermined. In reproduction, the whole digital data are read out by detecting start code 221 and the end code 224 of the predetermined line number.
However, the conventional structure described above, in which cassette numbers recorded in magnetic tapes are same with the numbers which are recognized by a user, has the following inconvenience. That is, when a user gives an instruction, on the display of a television screen, for deleting a certain program number which is registered for a cassette, the program data in the RAM 207 under the program number, which corresponds to the program data in the cassette under the same cassette number, is deleted from the memory of the RAM 207. However, the cassette number and the program data of the corresponding cassette are not deleted unless the user deletes these from the cassette. Therefore, when the program number which is deleted from the RAM207 is applied for recording a new program by using a new cassette, the same program number comes to exist in the VBIs of the magnetic tapes of the two or a plurality of different cassettes. Although the above inconvenience is prevented by applying different numbers for respective cassettes, the numbers increases, which creates another inconvenience of the difficulty of finding a desired program. The numerals of cassette numbers is better to be as small as possible for a user.
Also, there is a case that a plurality of cassette numbers are registered on one cassette by mistake, which is caused when the recording is performed in the state that the cassette numbers are failure in read after the cassette is inserted into the VTR or in the state that the VTR is erroneously operated. That is, when the recording is performed in such erroneous states, an improper cassette number is given and recorded into the magnetic tape, which results in the existence of a plurality of cassette numbers on one cassette. Although the cassette number can be corrected by a user in the case of erroneous loading of the cassette number, it is troublesome and not preferable.
The present invention addresses the above conventional problems and aims to provide a digital data recording and reproducing apparatus which solves the conventional problems with simple structure and registers a cassette number in a magnetic tape.
For realizing the above aim, the digital data recording and reproducing apparatus of the invention comprises a cassette number registering circuit for applying different cassette numbers for respective cassettes, a cassette number inserting circuit for inserting a cassette number in the form of a digital signal into the VBI of a video signal, a cassette number extracting circuit for extracting a cassette number from the VBI of a video signal, magnetic recording and reproducing means for recording and reproducing a video signal by using a magnetic tape, a display number registering circuit for searching out the smallest number from unused display numbers and applying the number as a new display number which corresponds to a new cassette number and is recognized by a user, a storing circuit for storing program data including the cassette number and the display number, a correspondence control circuit for searching, adding and deleting the program data.
The above structure enable that a cassette number recorded in a magnetic tape corresponds to a display number which can be recognized by a user on a television screen. Also, by registering a cassette number which is larger by one than the numbers used in the past for a new cassette, it is prevented that a plurality of cassettes have a same cassette number. Furthermore, by selecting the smallest number from the unused display numbers, deleted numbers can be used again. By using small display numbers, the handling of the program data becomes easy for a user. Also, it is advantageous that when a user deletes a display number registered for a cassette, the program data stored in the memory circuit, which is the same program data in the corresponding cassette, can also be deleted.